The invention relates to a method of transmitting graphic images, comprising the step of transmitting data defining pixels of a displayable subpicture, and the step of transmitting data invoking said subpicture for display on a receiver. The invention also relates to a television receiver and a display device for receiving and displaying said graphic images.
A method of transmitting graphic images is generally known as teletext. Herein, images are transmitted in the form of pages, each page comprising a plurality of character codes defining the alphanumeric and graphical characters of said page. Pixel patterns defining the commonly used characters are stored in a read-only memory section of the receiver. The known arrangements render it possible for characters, or series of characters, to xe2x80x9cflashxe2x80x9d, i.e. to be concealed and revealed at a predetermined frequency. This allows a dynamic effect to be added to a page.
More sophisticated teletext systems (level 3) provide a feature usually referred to as xe2x80x9cDynamically Redefinable Character Setsxe2x80x9d. This feature allows a page editor to define the pixel pattern of characters at the transmitter end, and to download said patterns to the receiver for storage in a random access memory prior to the transmission of the page.
It is an object of the invention to further improve the appearance of an image on screen.
According to the invention, the method is characterized in that the step of transmitting pixel defining data includes the transmission of pixel defining data for at least two motion phases of said subpicture to be displayed cyclically. The transmission step may include the transmission of a time code representing a time interval between displaying the successive motion phases of said subpicture. The graphic image can thus be enhanced with dynamic icons (xe2x80x9cdynaconsxe2x80x9d).